Voicing

Voicing refers to the vibration of the vocal folds during the production of a sound. When the vocal folds vibrate, the sound is described as voiced; when they do not, it is voiceless. Vowels are inherently voiced; many consonants can be either voiced or voiceless, producing a contrast that is phonemic in many languages.

Voicing is produced by the oscillation of the larynx during air passage from the lungs. The state of voicing depends on vocal fold tension, subglottal pressure, and airflow through the glottis. In many languages, the voicing distinction for stops and other obstruents is also realized acoustically via voice onset time: voiced consonants typically have shorter VOT, while voiceless ones have longer VOT and may be aspirated.

Voicing contrasts can be phonemic for several consonant classes (stops, fricatives, affricates) and can be affected by surrounding vowels and speech rate. Some languages reduce or neutralize voicing contrasts in certain positions or in rapid speech. In addition to the binary voiced/voiceless distinction, languages may employ other phonation types, such as creaky, breathy, or modal voice, on vowels and sometimes on consonants.

Acoustically, voicing manifests as a periodic waveform with a fundamental frequency and a regular harmonic structure; voiceless sounds show aperiodic noise and lack clear glottal pulses in spectrograms. Perception of voicing combines temporal cues (VOT) and spectral cues (harmonics, amplitude), and is robust across languages.

In transcription, voiceless and voiced consonants are indicated by distinct symbols in the IPA, with diacritics used to mark partial voicing or devoicing.